Transferring nanostructures from wafers to transparent substrates

Abstract

Embodiments of the present disclosure generally relate to methods of forming optical devices comprising nanostructures disposed on transparent substrates. A substrate, such as a silicon wafer, is provided as a base for forming an optical device. A transparent layer is disposed on a first surface of the substrate, and a structure layer is disposed on the transparent surface. An etch mask layer is disposed on a second surface of the substrate opposite the first surface, and a window or opening is formed in the etch mask layer to expose a portion of the second surface of the substrate. A plurality of nanostructures is then formed in the structure layer, and a portion of the substrate extending from the window to the transparent layer is removed. A portion of the transparent layer having nanostructures disposed thereon is then detached from the substrate to form an optical device.

What is claimed is: 
     
       1. A method of forming an optical device, comprising:
 depositing an etch mask layer on a first surface of a substrate; 
 forming an opening in the etch mask layer to expose a portion of the first surface of the substrate; 
 depositing a structure layer on a transparent layer, the transparent layer being disposed on a second surface of the substrate opposite the first surface; 
 forming a plurality of nanostructures in the structure layer over the opening in the etch mask layer; 
 depositing a protective layer over the plurality of nanostructures; 
 etching a portion of the substrate extending from the opening in the etch mask layer to the transparent layer; and 
 detaching a portion of the transparent layer having the plurality of nanostructures disposed thereon from the substrate to form an optical device, the detached portion of the transparent layer being aligned with the opening in the etch mask layer. 
 
     
     
       2. The method of  claim 1 , wherein the transparent layer is deposited on the second surface of the substrate prior to depositing the structure layer. 
     
     
       3. The method of  claim 1 , further comprising:
 providing the substrate having the transparent layer disposed on the second surface as a base prior to depositing the etch mask layer; and 
 removing the protective layer after detaching the portion of the transparent layer having the plurality of nanostructures disposed thereon. 
 
     
     
       4. The method of  claim 1 , wherein the structure layer comprises a material having a refractive index greater than about 1.8 and an absorption coefficient less than about 0.001. 
     
     
       5. The method of  claim 1 , wherein the structure layer comprises a material selected from the group consisting of titanium dioxide, gallium phosphide, gallium nitride, zinc oxide, tin dioxide, aluminum-doped zinc oxide, crystalline silicon, and silicon nitride. 
     
     
       6. The method of  claim 1 , wherein the substrate comprises silicon. 
     
     
       7. The method of  claim 1 , wherein the transparent layer comprises an oxide material. 
     
     
       8. The method of  claim 1 , wherein the portion of the substrate extending from the opening in the etch mask layer to the transparent layer is etched using an etchant comprising xenon difluoride, tetramethylammonium hydroxide, or potassium hydroxide. 
     
     
       9. The method of  claim 1 , wherein the substrate comprises silicon, the transparent layer comprises silicon dioxide, and the portion of the substrate extending from the opening in the etch mask layer to the transparent layer is etched using an etchant having a high selectivity to etch silicon compared to silicon dioxide. 
     
     
       10. The method of  claim 1 , wherein the plurality of nanostructures are formed using a nanoimprint stamp or a lithography process. 
     
     
       11. A method of forming an optical device, comprising:
 providing a silicon on insulator substrate as a base, the silicon on insulator substrate comprising a handle layer, a buried oxide layer disposed on a first surface of the handle layer, and a device layer disposed on the buried oxide layer; 
 depositing an etch mask layer on a second surface of the handle layer opposite the first surface; 
 forming an opening in the etch mask layer to expose a portion of the second surface of the handle layer; 
 forming a plurality of nanostructures in the device layer over the opening in the etch mask layer; 
 depositing a protective layer over the plurality of nanostructures; 
 etching a portion of the handle layer extending from the opening in the etch mask layer to the buried oxide layer; 
 detaching a portion of the buried oxide layer having the plurality of nanostructures disposed thereon from the handle layer to form an optical device, the detached portion of the buried oxide layer being aligned with the opening in the etch mask layer; and 
 removing the protective layer. 
 
     
     
       12. The method of  claim 11 , wherein the buried oxide layer comprises an oxide material. 
     
     
       13. The method of  claim 11 , wherein the portion of the handle layer extending from the opening in the etch mask layer to the buried oxide layer is etched using an etchant comprising xenon difluoride. 
     
     
       14. The method of  claim 11 , wherein the handle layer comprises silicon, the buried oxide layer comprises silicon dioxide, and the portion of the handle layer extending from the opening in the etch mask layer to the buried oxide layer is etched using an etchant having a high selectivity to etch silicon compared to silicon dioxide. 
     
     
       15. The method of  claim 11 , wherein the plurality of nanostructures are formed using a nanoimprint stamp or a lithography process. 
     
     
       16. The method of  claim 11 , wherein the device layer is selected from a group consisting of crystalline silicon, silicon nitride, and amorphous silicon. 
     
     
       17. A method of forming an optical device, comprising:
 providing a substrate as a base, the substrate comprising silicon; 
 depositing an etch mask layer on a first surface of the substrate; 
 forming an opening in the etch mask layer to expose a portion of the first surface of the substrate; 
 depositing a transparent layer on a second surface of the substrate, the second surface being opposite the first surface; 
 depositing a structure layer on the transparent layer, the structure layer comprising a material having a refractive index greater than about 1.8 and an absorption coefficient less than about 0.001; 
 forming a plurality of nanostructures in the structure layer over the opening in the etch mask layer; 
 depositing a protective layer over the plurality of nanostructures; 
 etching a portion of the substrate extending from the opening in the etch mask layer to the transparent layer; and 
 detaching a portion of the transparent layer having the plurality of nanostructures disposed thereon from the substrate to form an optical device, the detached portion of the transparent layer being aligned with the opening in the etch mask layer. 
 
     
     
       18. The method of  claim 17 , wherein the structure layer comprises a material selected from the group consisting of titanium dioxide, gallium phosphide, gallium nitride, zinc oxide, tin dioxide, aluminum-doped zinc oxide, crystalline silicon, and silicon nitride. 
     
     
       19. The method of  claim 17 , wherein the transparent layer comprises an oxide material, and wherein the protective layer is an encapsulation layer. 
     
     
       20. The method of  claim 17 , wherein the portion of the substrate extending from the opening in the etch mask layer to the transparent layer is etched using an etchant comprising xenon difluoride.